Flexible insulated ducts for air conditions systems have been suspended from overhead construction beams by circumferentially wrapped metal wire, metal strapping, fabric strips, rope or stapling wire. It has not been uncommon for suspension techniques of this type to result in ruptures of the outer wrapper or moisture barrier of the duct causing impairment of moisture resistance and at times even interfering with the capacity of the duct to carry air. An improvement over these earlier suspension means has been the use of metallic grommets crimped into a longitudinal seam of the outer wrapper or moisture barrier by hand or automatically by a crimping machine. There have been instances where the misplacing of such grommets have caused tears in the vapor barrier which worsen during the life of the system because of the weight of the duct. Also, some installations do not require grommets at all, or only along portions of the length of a given duct, and placing the grommets indiscriminately throughout the length of all ducts is unnecessary.